ONLY if you
R and Rc
Common wire from secondary side of cooling transformer (if 2 transformers).
Optional wirer save module.
Cooling power. Connect to secondary side of cooling system transformer.
Heating power. Connect to secondary side of heating system transformer.
1st stage heat relay. Or changeover valve for heat pumps.
1st stage compressor contactor.
2nd stage heat relay. Or heat pump auxiliary/Emergency heat relay.
2nd stage compressor contactor.
Heat pump system monitor.
Jumper Loop, a plug with a wire loop used to connect the R to the Rc terminals,
Leave jumper loop in place in single transformer systems. Remove (unplug) jumper
loop in two transformer systems.